std: Chunk writing to stdout on windows

This just takes a similar approach to reading stdin on windows by artificially
limiting the size of the buffers going in and out.

Closes #14940

src/test/run-pass/issue-14940.rs

@@ -0,0 +1,24 @@
+// Copyright 2012-2014 The Rust Project Developers. See the COPYRIGHT
+// file at the top-level directory of this distribution and at
+// http://rust-lang.org/COPYRIGHT.
+//
+// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
+// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
+// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
+// option. This file may not be copied, modified, or distributed
+// except according to those terms.
+
+use std::os;
+use std::io::{stdio, Command};
+
+fn main() {
+    let args = os::args();
+    if args.len() > 1 {
+        let mut out = stdio::stdout();
+        out.write(['a' as u8, ..128 * 1024]).unwrap();
+    } else {
+        let out = Command::new(args.get(0).as_slice()).arg("child").output();
+        let out = out.unwrap();
+        assert!(out.status.success());
+    }
+}